High-density lipoprotein inversely relates to its specific autoantibody favoring oxidation in thrombotic primary antiphospholipid syndrome

Abnormalities of the lipid profile partly explain the atherogenic tendency of systemic lupus erythematosus but the picture is unclear in thrombotic primary antiphospholipid syndrome (PAPS). Herein we compare the lipid profile, high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (CHO), apolipoprotein A (ApoA-I), apolipoprotein B (ApoB), triglycerides (TRY)), anti-lipoprotein antibodies, beta-2-glycoprotein I complexed to oxidized low-density lipoprotein (oxLDL-ss(2)GPI) and C-reactive protein (CRP) from thrombotic PAPS (n = 34), thrombotic patients with inherited thrombophilia (IT; n = 36), subjects persistently positive for antiphospholipid antibodies (aPL, n = 18) with no underlying autoimmune or non-autoimmune disorders and healthy controls (n = 28) and determined the reciprocal effects of anti-lipoprotein antibodies, the lipid profile, oxLDL-ss(2)GPI and CRP. Average concentrations of HDL (p < 0.0001), LDL (p < 0.0001), CHO (p = 0.0002), ApoA-I (p = 0.002) were lower in PAPS whereas average TRY was higher (p = 0.01) than other groups. Moreover, the aPL and PAPS group showed higher levels of IgG anti-HDL (p = 0.01) and IgG anti-ApoA-I (p < 0.0001) whereas the PAPS group showed greater average oxLDL-ss(2)GPI (p = 0.001) and CRP (p = 0.003). Within the PAPS group, IgG anti-HDL correlated negatively to HDL (p = 0.004) and was an independent predictor of oxLDL-ss2GPI (p = 0.009). HDL and ApoA-I correlated negatively with CRP (p = 0.001 and p = 0.007, respectively). IgG anti-HDL may hamper the antioxidant and anti-inflammatory effect of HDL favoring low-grade inflammation and enhanced oxidation in thrombotic PAPS.

Identification of drug metabolites in biological matrices by intelligent automated liquid chromatography/tandem mass spectrometry

A rapid and systematic strategy for the identification of drug metabolites in biological matrices based on liquid chromatography-tandem mass spectrometry (LC/MS/MS) techniques was utilized for the identification of drug metabolites of the HIV protease inhibitor Indinavir. This strategy integrates intelligent realtime mass spectrometry with HPLC detection and a predictive strategy for detecting metabolites arising from common biotransformations, to rapidly elucidate structures of drug metabolites. Structures of metabolites generated from in vitro incubation mixtures of Indinavir were characterized from a single chromatographic analysis using the automated LC/MS/MS methodology, thus reducing data acquisition time and improving efficiency.

Pharmacokinetics of verapamil and norverapamil during long-term oral therapy

Serum concentrations of verapamil and its pharmacologically-active metabolite, norverapamil, were measured in six patients with angina at rest after six to fifteen months of therapy. Optimal daily doses were selected during a previous in-hospital titration period and ranged from 240 to 640 mg per day. There was no significant relationship between dose, corrected for body weight, and area under the verapamil serum concentration-time curve (AUC). The mean apparent oral clearance of verapamil was highly variable with a mean of 21.9 +/- 9.1 ml/min/kg and a range of 7.7 to 32.0 ml/min/kg. The ratio of verapamil AUC to norverapamil AUC, used to assess accumulation kinetics of parent drug and metabolite, was less than 1.0 in five of six patient (mean 0.93). However, one patient with verapamil concentrations ranging from 300 to 900 ng/ml had a ratio of 1.37 suggesting saturation of the enzymes that convert verapamil to norverapamil. When the relationship between serum concentration at the end of the dosing interval and angina frequency was studied, it was observed that patients in whom angina was completely suppressed had concentrations greater than 160 ng/ml and patients with poor control (greater than 5 anginal episodes per week) had concentrations less than 60 ng/ml. The findings suggest that the oral clearance of verapamil following long-term (greater than 6 mo.) administration may be different than after short-term therapy and that it is difficult to predict verapamil serum concentrations and antianginal effect during long-term oral therapy. Individualizing verapamil therapy to maintain serum concentrations greater than 100 ng/ml may improve therapeutic response and appears to more reliably predict response than daily dose.